With the formula: l Mix = 2 / (1 / l 1 + 1 / l2), it is possible to mix any two wavelengths to find the wavelength of the mixture. If the initial wavelengths are located several spectrals apart, the results will be non linear because each successive spectral is half the width of the one before it. In the case where the mix is not in the visible spectral, S11, the wavelength will need to be normalized to know what color it is.

The above formula can be rearranged into another form that will find lX when lRef and lMix are both known. This will let you choose the color of the mix, and use another color of your own choice as a test reference. The calculated value gives you the color you need to use with the reference wavelength to get the chosen mix. This formula is given as:

lX = lMix / (2 - ( lMix / lRef ))

Here the idea is to choose a mixture wavelength within the visible spectral S11, a color that can be seen and identified. Then it will be possible to mix various color sources with a color that has a known wavelength, lRef . When the chosen color is observed, the color under test will have the wavelength calculated by the formula.